Quick Links:

R100T Restore Project
HTML tutorial
(sample) Project
HTML tutorial

Sunday, February 12, 2012

Doubling Down

The project is moving along but has encountered some unexpected obstacles.  My lack of posting for the past couple of weeks is not an indicator that I've slowed down, just that I've been "up to my elbows" so to speak -- both with grease/grime and with a lot of work I did not anticipate.  Many times I think, "hey, I should take a picture of this" then I realize I'd have to spend 5 minutes scrubbing the grease off my hands so that I could use the camera, so instead I just move along.  I have paused occasionally and snapped some interesting pics which I'll share with you.

Here are some of the bigger updates related to what I call the "discovery phase" of the project -- namely where you are learning about the history and issues with the project ...

Working with Bob (Bob's Motorwerks) was a learning experience.  He has many, many years of hands- on experience working on Airheads, and a ton of wisdom as a result.  Rebuilding a transmission that you did not personally "wear out" is a bit like reading a mystery novel (not that I ever do that).  All the gears and mysteries are hidden inside the case, and it is not until you open it up that you find out what the story really is.  Well my story started by me removing the transmission and sending it to Bob, and it got even more interesting when he called me a few days later after he was able to open the case and assess the issues. That hopeful/excited feeling I had in my stomach was quickly dispatched when the first words he said to me were, "In all my years rebuilding transmissions, I've never seen this kind of damage ... it looks like the previous owner (PO) was trying to do wheelies, or some other monkey business, over and over ... the front lay shaft gear and thrust piece are all busted up ... whaa .. whaa ... wahaaaaa ..."   Actually, he did not sound like one of Charlie Brown's teachers, but he went through a very technical description of which gears were busted up and how ridiculous the whole thing was.  The big problem is that BMW doesn't even sell the input lay shaft parts anymore and last time they did, it was around $1,100 for the shaft complete with gears.  Fortunately for me, Bob is a very resourceful individual with a lot of "in good shape used parts" laying around and he also has access to a 20 ton press.  He took good care of me and although the news was not what I had hoped for, the final bill was not a lot more than I expected:

Transmission boxed up and waiting for UPS to pickup and deliver to Bob.

Yea! Transmission back from Bob.

Emmery inspecting the box for shipping damage!  ;-)

Emmery pushing the box toward the garage so she can open it.

Emmery inspecting the contents of the box (If you're wondering why the box is full of plastic oil quarts, Bob uses empty ones as shipping ballast to secure the transmission.  Very smart!)

Emmery taking the oil quarts out.

The "re-habbed" tranny waiting to be installed.  Those acid stains were there before I sent it in to Bob, I'll have to polish them off before re-installation.

Left to Right:  Lay shaft front gear; thrust piece; 15deg input gear with broken tooth.

Input gear shows sheering on the tip.

Thrust piece is also badly worn.

Lay shaft float gear has badly scarred gear teeth.

Drive Train:
Upon discovering the evidence uncovered in the transmission (that the PO was trying to wheelie repeatedly, or repeatedly riding on washboard gravel roads, I was advised to inspect my clutch, (topic of another post to come) the drive shaft, (BMWs have drive shafts not chains) and the final drive for damage.  Like they say, where there is smoke, there is fire.  In this case, additional damage caused by PO:

Reader,  meet the drive shaft (inside the black hollow swing arm on the left) and final drive (the silver thing with the drum brake lever on it).

Drive Splines:  the circle with the teeth on it are the drive splines.  If you look at the individual splines look at the width of the spline nearest you compared to the portion farthest from you (where it does not wear).  It is about 1/2 to 1/3 the original width... this is caused by neglect.

That is the U Joint.  Fortunately, it was in pretty decent condition.    

Unanticipated Issues:
As if the overly worn transmission, worn drive splines, rusty drive shaft tube, worn U Joint were not bad enough news, the discovery journey did not end until I followed the "wheelie trail" to the bitter end.  I discovered two other issues that I'll need to monitor:

Rim just above the valve stem shows slight bend/flat spot.  The tire bead looks ok so I can probably ignore the issue ... but 'cmon this is a touring bike not a MX bike!

Cracked Frame:  the frame just above and to the right of the round hole (where rear brake pedal attaches) is cracked.  My neighbor has a '77 R100/7 that he is restoring and has two of these cracks in the same spot.  Fortunately this is a non critical area of the frame, so we'll just spot weld it in place and repaint.

The end of the bad news trail for now.  And now I'll post some other news of progress ....


  1. With the lack of OEM new parts, do you plan to try and have the damaged gears repaired for spares and/or later trade? Ray T.

  2. Good idea but not even sure where to start on that idea. Even the experts who work on these transmissions don't even try that one, they look for good quality used components instead. Each of those bits cost me about $35 a piece, so whatever repair process used would have to be less expensive than that. ummm....